Tested: Pro Circuit YZ250F & YZ450F T-5 Exhaust Systems

Let's face it, MXers are just about the most vain and materialistic sports enthusiasts out there. If you're not rocking the latest and greatest of whatever you can get your hands on, why even show up to the track? When it comes to the body, the first thing to change up is gear. For the bike? Well, exhaust systems of course! It is the rare rider that keeps their stock system on for before it actually needs to be replaced. But there is a lot more to an exhaust system than just looks. Pro Circuit knows a thing or two about performance (and the Gucci stuff as well) and their latest price point exhaust offering, the T-5, offers plenty of gains and won't break the bank. Before heading out the to track with the T-5 installed on both our 2013 YZ250F and YZ450F, Pro Circuit still needed to do their sound testing on the Yamahas for the new model year. During the test, we had John Mitcheff explain what goes into their testing process.

While the 2013 Yamaha YZ250F is no slouch out on the track, the fact remains that it is the only remaining carbureted full size motocross machine among the big five OEMS. As such, it can feel slightly down on power down low when compared to it’s fuel-injected brethren, but all it takes are the right mods to put the small bore four-stroke right back in the mix. Of course, the first (and easiest) power mod that most people will make, is a quick change of exhaust systems.

As Pro Circuit’s, John Mitcheff explained, the Yamahas are just about the quietest stock bikes, so there is plenty of room to go louder, add some ponies, and still fall within legal AMA sound limits. Throwing the T-5 Stainless Steel pipe on is a snap, and while it is not as light as the Ti-5 titanium version, the pipes share the same exact design, which means the T-5 also has the same performance gains as well.

Pro Circuit explains their RC-4 resonance chamber.

What we’ve found on the stock YZ250F is that it needs a little help down low and getting a little extra grunt out of the motor. The T-5 pipe and RC-4 header made a night & day difference when compared to the stock unit. Not only does the Pro Circuit system add a nice throaty note compared to the very muffled stock system, it drastically helps increase the bottom end hit.

Whether coming out of tight rutted turns or hitting quick seat bounce jumps, it is much easier to stay within the meat of the power without needing to dab the clutch. While midrange power remained about the same, up top the T-5 system allowed the power to continue climbing beyond the RPM range where the stock system normally falls flat.

YZ450F

Where the YZ250F needs a little help to get the power up to where most would like, its bigger brother has no troubles in the power department. In fact, Yamaha changed the mapping for 2012 to make the YZ450F’s bottom end hit more manageable and progressive.

However, perhaps due to the very muted stock exhaust system, the power still seems to fall flat in the upper ranges of the RPMs. Again, enter the Pro Circuit T-5 exhaust system. While there are plenty of tracks in SoCal where you will almost never be tapped out on a 450 (unless your RV2, RD5, JS7, or CR22) such as Milestone or Perris Raceway, other open tracks like Glen Helen or Cahuilla Creek offer plenty of opportunities to open the floodgates and see what happens.

It’s on those long, whooped-out, straights where you feel a combination of elation and pure fear that the T-5 shows its mettle. Just like with the YZ250F, the PC system allows the power to continue climbing where the stock system would normally sign off in the upper ranges.

While the pipe helps throughout the powerband, it’s most noticeable contribution is definitely at the high end of the RPMs. If you aren’t a gram saving nerd, the Pro Circuit T-5 exhaust system is an excellent option that is well under a grand.